Thursday, September 04, 2014

Scientific Consensus

A very good article on what "scientific consensus" is and what it actually means on Ars Technica. This is in light of the attack on scientific consensus related to global warming.

In an earlier discussion of science's standards for statistical significance, we wrote, "Nobody's ever found a stone tablet etched with a value for scientific certainty." Different fields use different values of what they think constitutes significance. In biology, where "facts" are usually built from a large collection of consistent findings, scientists are willing to accept findings that are only two standard deviations away from random noise as evidence. In physics, where particles either exist or don't, five standard deviations are required.

While that makes the standards of evidence sound completely rational, they're also deeply empirical. Physicists found that signals that were three standard deviations from the expected value came and went all the time, which is why they increased their standard. Biologists haven't had such problems, but other problems have popped up as new technology enabled them to do tests that covered tens of thousands of genes instead of only a handful. Suddenly, spurious results were cropping up at a staggering pace. For these experiments, biologists agreed to a different standard of evidence.

People who don't know any better tend to lump things into simple terms, as if such a thing can be done. I've always said that in science, there is such a thing as a degree of certainty, that in some areas, the certainty is stronger than in others. The same can be said about the level what we accept something as valid evidence, or at least, valid enough. The article accurately describes why in one part of science, a loser level is sufficient, while in another part of science, a stricter level is needed. These are all based on experience and based on what has happened before, but to be able to do that, one MUST be well-experienced in what is going on in that particular field!

What it comes down to is that people who are experts in certain fields tend to have a "feel" on when something becomes convincing, or at the very least, there is a serious consideration on the validity of something. This is hard to do when you are an outsider. It is not because it is a closed society. Rather, it is just that one needs to have a long set of knowledge and experience in the field to know when something is valid.

This is an article that laymen, and especially politicians, should read.


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